1. Field of the Invention
The present invention is directed to a starting element for an engine, particularly having a torque converter or a hydrodynamic torque converter with a housing and a guide pin for centering the torque converter during assembly.
2. Description of the Related Art
Hydrodynamic torque converters are often used as a starting element in motor vehicles with automatic transmissions, i.e., the force is transmitted via the hydrodynamic converter during starting or accelerating from a stationary condition. After starting, the converter can be bypassed by a converter lockup clutch to increase efficiency and minimize converter losses. A starting element or hydrodynamic starting element in this sense is also a hydro clutch in which no torque conversion takes place because, in contrast to the hydrodynamic torque converter, it has no stator causing the torque increase. In addition to hydrodynamic coupling devices of this kind, other forms of wet-running and dry-running elements, e.g., centrifugal clutches, can also be used as starting elements.
When mounting a starting element, for example, a torque converter or hydrodynamic torque converter, on the engine, for example, on the flywheel, it is necessary to center the crankshaft axis and rotational axis of the torque converter as exactly as possible with respect to one another so that there is no axial misalignment that could lead to losses and imbalances in the drivetrain. To this end, a central guide pin is often arranged at the housing or at the housing cover or housing part of the torque converter that faces the drive motor. During assembly, this guide pin engages in a corresponding bore hole in the crankshaft or flywheel so that the rotational axes of the two units are aligned with one another. After centering by means of the guide pin, the two units are often screwed together by means of flexplates, i.e., flexible connection elements which compensate for axial oscillations.
After screwing together, the guide pin essentially serves no purpose and can even be an impediment. For example, an axial oscillation, a slight temporary axial offset or a tilting of the torque converter relative to the drive unit can be compensated by the connection through the flexplate. However, force is also transmitted through the guide pin during movements of this kind and enters the housing of the torque converter, which can hamper compensation. In addition, force entering at the guide pin, for example, in the weld connections typically used between guide pin and the cover of the torque converter housing, can lead over the long term to material fatigue and cracks in the housing or housing cover.
U.S. Pat. No. 6,277,027, for example, shows a center pin which is turned or milled from a rigid material, for example, from a solid metal material, and which is arranged at the housing of a torque converter for centering. The solid and stable center pin transmits all of the forces directly into the housing of the converter and can accordingly lead to the tensions or damage to the converter housing described above.
U.S. Pat. No. 4,523,916 describes a torque converter in which the guide pin is formed as part of the housing, which clearly leads to the same problems as well as a rigid connection of the guide pin to the flexplates used for connecting to the drive unit.
Therefore, there is a need to ensure an improved force absorption connection between the guide pin and the housing of the starting element.